SERPINA1 and cancer: To evaluate the pan-cancer robustness of our 4-gene signature (MAOB, IGFBP2, SERPINA1 and LGR6), we leveraged the ICBatlas database—comprising 93,000+ patients across 18 cancer types (including 12 cancers with multi-omics profiling) and 30 immune checkpoint inhibitor (ICI) treatment cohorts.